For example, many entrepreneurs file taxes as individuals and would be impacted if the tax rate on incomes exceeding $250,000 was raised.
(Read more: 2012 on Main Street: The Year of Living With Uncertainty)
"Then we can't put the money back into capital," said Alfano of the restaurant chain based in Van Nuys, Calif. Founded in 1985, the chain employees about 400 workers. She made the comments on CNBC's "Street Signs" on Friday.
Many small-business owners are monitoring the "cliff" talks. "The uncertainty right now will probably affect 2014" business, said David Martin of HJ Martin & Son, which provides flooring, carpeting and other interior construction services. Based in Green Bay, Wis., the business was founded in 1931 and employees more than 500 people.
(Read more: Five Key Issues Facing Small Business in 2013)
Payroll Tax Effect
In contrast to the construction business that can operate on a months-ahead time frame, restaurants such as Maria's Italian Kitchen would be immediately impacted by a payroll-tax hike if a debt deal isn't reached.
A small paycheck means consumers scrutinize their spending habits including restaurant meals. "That's going to be significant for a lot of people and they're going to think about it," Alfano said.
With so much uncertainty hanging over small companies, Main Street—a traditional driver of new jobs and economic growth after a downturn—largely has been at a standstill in 2012. (Read more: Amid 'Fiscal Cliff' Stalemate, Main Street Deteriorates)